Complementary photoelectrochemical performances between dual heterojunctions and homojunction to achieve efficient solar water splitting of ZnIn2S4-based photoanode

The broken verge of carrier separation efficiency is invaluable factor to enhance photoelectrochemical performances of ZnIn2S4-based dual heterojunction. Hence, additional internal electric field is introduced when hexagonal/cubic ZnIn2S4 homojunction interface is used as medium to tandem Sb2S3/hexagonal-ZnIn2S4 and cubic-ZnIn2S4/Cu2S heterojunctions. The enhanced photoelectrochemical properties of Sb2S3/hexagonal/cubic ZnIn2S4/Cu2S are initiated through complementary properties of heterojunctions and homojunction components: (i) carrier separation efficiency verge of heterojunctions is broken to 56.29 % due to cooperation of homojunction, (ii) photoinduced carrier excitation energy homojunction is reduced to 2.06 eV with the modification of heterojunctions, (iii) built-in electric field is reinforced and electron delocalization of homojunction is enhanced by heterojunction, (iv) photoelectrochemical reaction sites of homojunction are increased through optimizing surface states effect of heterojunctions. As a result, the upgraded to 31.80 times higher water oxidization photocurrent density of 4.77 mA/cm2 is achieved by Sb2S3/hexagonal/cubic ZnIn2S4/Cu2S with decreased reaction overpotentials to 0.60 V. This work raises new thoughts on modified PEC performances of ZnIn2S4 via composite methods. •The photocurrent density of 4.77 4.77 mA/cm2 is achieved by hetero-homo-heterojunction at 1.23 V vs. RHE.•The complementary PEC performances are displayed between heterojunctions and homojunction.•Photoinduced carrier separation efficiency verge of heterojunctions is broken due to cooperation of homojunction.•The electron structure and carrier behavior of homojunction is optimized by heterojunctions.•PEC reaction sites of homojunction are increased through optimizing surface states effect of heterojunctions.